The worst is trade #4:
(-100k * (4.551% + 1.5%) + 0% * some_millions_Yen ) * 2/360 = -33.62 USD
(So, if you hold for a year, that's 6051 USD in interest charges!)
Considering that you only need 2000 USD margin to open
such a position, the interest charges of 33USD are 1.65%
of your...